Background and objectives: Male sex is a risk factor for poor neurodevelopmental outcome following preterm birth. The investigators aimed to investigate gender-related differences in amplitude-integrated electroencephalography (aEEG) and to correlate these findings with neurodevelopmental outcome.

Methods: Preterm infants born <30 weeks' gestational age between 2000 and 2002 were prospectively included. aEEGs obtained within the first two weeks of life were evaluated and classified according to background activity, sleep-wake cycling (SWC) and seizure activity. Outcome was assessed at three years.

Inclusion Criteria:

• born<30 weeks gestational age
• who had aEEGs in first 2 weeks of life
• who were assessed for outcome at 3 years of age

Exclusion Criteria:

• born>30 weeks gestational age
• had no aEEGs in first 2 weeks of life
• lost for follow-up at 3 years

preterms born < 30 weeks gestational age who had aEEG measurements within the first 2 weeks of life who had assessment of outcome at 3 years corrected age